clk: core: copy parent_names & return error codes

This patch cleans up clk_register and solves a few bugs by teaching
clk_register and __clk_init to return error codes (instead of just NULL)
to better align with the existing clk.h api.

Along with that change this patch also introduces a new behavior whereby
clk_register copies the parent_names array, thus allowing platforms to
declare their parent_names arrays as __initdata.

Signed-off-by: Mike Turquette <mturquette@linaro.org>

1 files changed, 53 insertions, 12 deletions

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index ddade8759ea9..8f7c3849c8f6 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1185,34 +1185,41 @@ EXPORT_SYMBOL_GPL(clk_set_parent);
  * very large numbers of clocks that need to be statically initialized.  It is
  * a layering violation to include clk-private.h from any code which implements
  * a clock's .ops; as such any statically initialized clock data MUST be in a
- * separate C file from the logic that implements it's operations.
+ * separate C file from the logic that implements it's operations.  Returns 0
+ * on success, otherwise an error code.
  */
-void __clk_init(struct device *dev, struct clk *clk)
+int __clk_init(struct device *dev, struct clk *clk)
 {
-        int i;
+        int i, ret = 0;
         struct clk *orphan;
         struct hlist_node *tmp, *tmp2;
 
         if (!clk)
-                return;
+                return -EINVAL;
 
         mutex_lock(&prepare_lock);
 
         /* check to see if a clock with this name is already registered */
-        if (__clk_lookup(clk->name))
+        if (__clk_lookup(clk->name)) {
+                pr_debug("%s: clk %s already initialized\n",
+                                __func__, clk->name);
+                ret = -EEXIST;
                 goto out;
+        }
 
         /* check that clk_ops are sane.  See Documentation/clk.txt */
         if (clk->ops->set_rate &&
                         !(clk->ops->round_rate && clk->ops->recalc_rate)) {
                 pr_warning("%s: %s must implement .round_rate & .recalc_rate\n",
                                 __func__, clk->name);
+                ret = -EINVAL;
                 goto out;
         }
 
         if (clk->ops->set_parent && !clk->ops->get_parent) {
                 pr_warning("%s: %s must implement .get_parent & .set_parent\n",
                                 __func__, clk->name);
+                ret = -EINVAL;
                 goto out;
         }
 
@@ -1308,7 +1315,7 @@ void __clk_init(struct device *dev, struct clk *clk)
 out:
         mutex_unlock(&prepare_lock);
 
-        return;
+        return ret;
 }
 
 /**
@@ -1324,29 +1331,63 @@ out:
  * clk_register is the primary interface for populating the clock tree with new
  * clock nodes.  It returns a pointer to the newly allocated struct clk which
  * cannot be dereferenced by driver code but may be used in conjuction with the
- * rest of the clock API.
+ * rest of the clock API.  In the event of an error clk_register will return an
+ * error code; drivers must test for an error code after calling clk_register.
  */
 struct clk *clk_register(struct device *dev, const char *name,
                 const struct clk_ops *ops, struct clk_hw *hw,
                 const char **parent_names, u8 num_parents, unsigned long flags)
 {
+        int i, ret;
         struct clk *clk;
 
         clk = kzalloc(sizeof(*clk), GFP_KERNEL);
-        if (!clk)
-                return NULL;
+        if (!clk) {
+                pr_err("%s: could not allocate clk\n", __func__);
+                ret = -ENOMEM;
+                goto fail_out;
+        }
 
         clk->name = name;
         clk->ops = ops;
         clk->hw = hw;
         clk->flags = flags;
-        clk->parent_names = parent_names;
         clk->num_parents = num_parents;
         hw->clk = clk;
 
-        __clk_init(dev, clk);
+        /* allocate local copy in case parent_names is __initdata */
+        clk->parent_names = kzalloc((sizeof(char*) * num_parents),
+                        GFP_KERNEL);
+
+        if (!clk->parent_names) {
+                pr_err("%s: could not allocate clk->parent_names\n", __func__);
+                ret = -ENOMEM;
+                goto fail_parent_names;
+        }
+
+
+        /* copy each string name in case parent_names is __initdata */
+        for (i = 0; i < num_parents; i++) {
+                clk->parent_names[i] = kstrdup(parent_names[i], GFP_KERNEL);
+                if (!clk->parent_names[i]) {
+                        pr_err("%s: could not copy parent_names\n", __func__);
+                        ret = -ENOMEM;
+                        goto fail_parent_names_copy;
+                }
+        }
+
+        ret = __clk_init(dev, clk);
+        if (!ret)
+                return clk;
 
-        return clk;
+fail_parent_names_copy:
+        while (--i >= 0)
+                kfree(clk->parent_names[i]);
+        kfree(clk->parent_names);
+fail_parent_names:
+        kfree(clk);
+fail_out:
+        return ERR_PTR(ret);
 }
 EXPORT_SYMBOL_GPL(clk_register);